I dunno... my daughter is 10, and my son is 6 and going to 2nd grade.
They both just wear what they, want or like.
They each have their own personality and I let them wear what their "taste" is as long as it is not skanky/trashy clothing.
Which my kids, they don't like skanky clothing anyway. Though some of their classmates, do. Whatever.
Anyway, my son uses the word "awesome" a lot, versus "cool."
I just tell my kids, that despite what OTHER kids say... they have their own, minds, and preferences. So, go according to, themselves.
And they do.
But of course, there are overall likes or dislikes, per age or grade level, per what kids like to wear or have. Fine.
But main thing is, at least for my kids, that they think on their own, and are their own, person. Which I just taught them about since they were Toddlers. Because, I knew, once they entered into Elementary school, there would be all sorts of influences with everything.... due to other kids. But my kids will go according to their own personal cues. Thus far, they have been aware and know themselves. Versus just going according to follow the sheep.